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Wednesday, 31 July 2013

Antarctic melt

Unlike
the Arctic Circle up north, where once-permanent sea ice began
melting and miles of permafrost began thawing decades ago, the ground
ice in Antarctica’s Garwood Valley was generally considered stable.
In this remote polar region near the iceberg-encrusted Ross Sea,
temperatures actually became colder from 1986 to 2000, then
stabilized, while the climate in much of the rest of the world warmed
during that same period.

But
now, the ice in Antarctica is melting as rapidly as in the Arctic.

That’s
not because temperatures are rising. A
team of researchers has discovered that
increased solar radiation is thawing ground ice in Garwood Valley at
an accelerated rate, disrupting normal seasonal ice patterns.

The
cause of the increased solar radiation is, for now, uncertain,
although it is related to changes in weather patterns. More research
will be required to determine why it is happening.

“I’m
a geologist—I look down,” explained
Joseph Levy,
one of two University of Texas at Austin scientists on the research
team and co-author of the research
paper in Scientific Reports.
“The next step is to figure out what’s driving this change in
sunlight patterns. It’s going to involve working with
meteorologists and climate modelers.”

Antarctica
is predicted to warm during the coming century. As a result, the
ground ice could melt even more quickly, which would cause more
serious sinking and buckling of the landscape.

Few
creatures will notice the collapse of these barren landscapes, and
the ones that will are mostly microscopic. The Garwood Valley is home
to microorganisms, lichens, and algal mats (thin layers of algae and
cyanobacteria that are found in the continent’s seasonal streams).
Its top predator, according to Levy, is a nematode—a roundworm that
is only a millimeter long. But this ancient, almost untouched part of
the world has surprising scientific value.

“What
makes Antarctica work, and what makes science there important, is not
that it’s exotic and far away, but that it tells us fundamental
things about how biological systems work, and how the earth system
works,” Levy said. “If you want to understand how organisms are
going to respond to climate change—whether they are people, crops,
or livestock—[then] a good thing to do is to look at the simplest
organism you can find, like a nematode [or] an algal mat, and ask,
‘How is this creature adapting?’”

Levy
spends about two months* every year in Antarctica’s dry valleys,
documenting how they are changing. When he arrives in October,
temperatures are around -22 degrees Fahrenheit. It is so cold that
almost everything freezes— food, batteries, electronics, beer, etc.
The scientists have to zip their laptops inside their parkas to warm
them up enough to operate. Antarctica’s harsh conditions are the
earth’s best approximation of life in another cold, dry place that
Levy studies: Mars.

Despite
the challenges, Levy says the work is exciting, and the location is
exotic. To get there, the research team takes a regular commercial
airliner to New Zealand. From there, they board a
U.S. military plane
that flies them to McMurdo
Station,
a U.S. research center located on an island in the Ross Sea. Then,
the team is flown by helicopter to Garwood Valley. During the
Antarctic summer, they are among approximately 50 people living and
conducting research in an area the size of Delaware.

“You’re
alone with nature, and you can really explore to your heart’s
content,” Levy said. “You can run your experiments without fear
of interference, without worry about it getting dark. In the summer,
it’s light 24 hours a day. It’s a place where you wake up in the
morning, you have a question, and you go out and answer it.”

He
describes the area as “beautiful in a desolate kind of way”—a
place of “sharp mountain peaks and wide, U-shaped valleys.” As
someone who has spent a great deal of time in this remote place, he
is familiar with the surprising ways in which it has recently
changed.

“Every
year that I’m back, the ice cliff is different,” said Levy,
referring to a research site in Garwood Valley that was brought to
the scientists’ attention by a helicopter pilot. “Every year you
come back, and basically, the hill [looks] like a big backhoe came in
and scooped out the equivalent of a couple of cubic yards of ice and
sediment.”

This
is simply the effect that increased solar radiation has had on
Garwood Valley. But what about global warming? For now, Antarctica is
shielded from parts of the global climate system by notoriously
strong winds and ocean currents that circle the continent, keeping
cold air in and warm air out. But fifty years from now, Levy
says, global warming will have reached Antarctica, potentially
producing more dramatic changes.

And
if temperatures rise a couple of degrees by the end of the century,
as predicted, then more Antarctic ice will melt and destabilization
will occur along the continent’s coasts.

The
accelerated melting of the permafrost in Garwood Valley, Levy
explained, serves as a “crystal ball” that provides insights into
Antarctica’s future.

“The
big concern is that the beginning of accelerated melting of the
permafrost in the dry valleys is a sign of things to come,” Levy
said. “It’s not the end of Antarctica as we know it, but it may
be the beginning of the end. It’s a sign that places we think are
stable, places where we don’t have an impact, actually, our
footprint can be felt there. It’s important to study these places
[and] get that baseline data now, because in the coming decades, this
is where change is really going to be apparent.”

*Clarification:
this article originally stated that Levy spends five months in
Antarctica every year. That is the length of the season. Levy spends
around two months there.